Some jib cranes are arranged, for example, in shipbuilding yards for use in transportation of heavy burdens. This kind of jib crane comprises an upper revolving table and a jib protruding from the revolving table (see, for example, Patent Literature 1 showing a climbing crane as jib crane). The jib has a base end pivoted on the revolving table and may be derricked through lead-in or pull-out of derricking wire ropes. A hanger such as a hook is suspended from a tip of the jib via hoisting wire ropes and a work of lifting and landing a burden hooked to the hanger, i.e., a burden handling work is carried out by reeling and unreeling the hoisting wire rope.    [Patent Literature 1] JP2001-130870A